Dovetail Plates

Dovetail Standards, Length and Stiffness

Two standards dominate, and the difference between them is not just width, it is torsional stiffness, which is what actually stops a heavy tube from twisting under a guiding correction.

• Vixen-style, approximately 44 mm: Light, near-universal on entry and mid-level mounts, and appropriate for visual loads and small imaging refractors up to a few kilograms.
• Losmandy-style, approximately 75 mm: Substantially stiffer in torsion, the correct choice for heavy tubes and for imaging where differential flexure would otherwise show in your stars.
• Length and balance range: A longer bar gives more fore-and-aft adjustment, which helps when adding a heavy camera train shifts the balance point well behind the rings.
• Slotted versus drilled: Slotted bars allow continuous ring positioning; drilled bars fit specific hole patterns and are usually stiffer for the same mass.
• Accessory rails: Short bars mounted on top of rings for guide scopes, cameras and finders, keeping accessories on the optical axis rather than cantilevered.
• Dual-standard plates: Bars machined to fit both saddle types, useful when moving one telescope between mounts.

Why Choose David Astro for Dovetail Plates

Flexure is diagnosed rather than guessed at. We help you find it before you buy a replacement for the wrong component.

• Saddle compatibility confirmed: We verify what your mount's saddle actually accepts, including dual-fit saddles that grip a narrow bar on its edges rather than its faces.
• Length sized to your balance: We account for the rearward shift a filter wheel and camera introduce, so you are not left with the rings at the very end of the bar.
• Machined quality: We stock bars whose dovetail angles are cut accurately enough to seat fully in a saddle, which cheap extruded bars often do not.
• Authorized dealer: Genuine hardware with manufacturer warranty, stocked domestically and ready to ship.

Dovetail Plates in Canada: Frequently Asked Questions

How long a dovetail should I buy?

Long enough that your rings sit near the middle of the bar with the camera attached. If the rings end up at the very front to achieve balance, the bar is too short and you have lost adjustment range.

Is a Losmandy bar overkill for a small refractor?

Often yes, and the extra mass counts against your payload. Below about 7 kg total, a well-machined Vixen bar is usually adequate unless your mount's saddle is Losmandy only.

Can a dovetail cause guiding problems?

Yes. An undersized or poorly seated bar twists under correction, producing errors that look like tracking faults. If guiding degrades at particular tube angles, check the dovetail seating first.

Do you stock bars for specific telescopes?

We carry model-specific bars for many common tubes as well as universal slotted plates. Tell us the telescope and we will confirm the hole pattern.

Sizing a dovetail?

Send us your mount, tube and camera weight and we will specify the bar. Canadian stock, fast domestic shipping.